Hi Kurt, Thanks for the details. When you say the job is failing, is it process hanging or abort? Are there any error messages? My suspicion is that slurm is preventing extra process to be launched since you have assigned all the resources to the first two MPI processes. Could you try increase the ntasks in the batch command? -- Hui Zhou ________________________________ From: Mccall, Kurt E. (MSFC-EV41) <[email protected]> Sent: Friday, January 7, 2022 3:33 PM To: Zhou, Hui <[email protected]>; [email protected] <[email protected]> Cc: Mccall, Kurt E. (MSFC-EV41) <[email protected]> Subject: Re: Slurm and MPI_Comm_spawn Thanks for the reply, Hui. configure --prefix=/home/kmccall/mpich-install-4.0b1 --with-device=ch3:nemesis --disable-fortran -enable-debuginfo --enable-g=debug The program is run via sbatch, which is given a bash script as an argument. sbatch --nodes=2 --ntasks=2 --cpus-per-task=24 <bash_script> The bash script calls mpiexec: mpiexec -print-all-exitcodes -enable-x -np 2 -wdir ${work_dir} -env DISPLAY localhost:10.0 --ppn 1 <cmd> From: Zhou, Hui <[email protected]> Sent: Friday, January 7, 2022 2:39 PM To: [email protected] Cc: Mccall, Kurt E. (MSFC-EV41) <[email protected]> Subject: [EXTERNAL] Re: Slurm and MPI_Comm_spawn MPICH uses PMI 1 by default. How is your MPICH configured? And how do you run your program, is it via srun? -- Hui Zhou From: Mccall, Kurt E. (MSFC-EV41) via discuss <[email protected]<mailto:[email protected]>> Date: Friday, January 7, 2022 at 2:21 PM To: [email protected]<mailto:[email protected]> <[email protected]<mailto:[email protected]>> Cc: Mccall, Kurt E. (MSFC-EV41) <[email protected]<mailto:[email protected]>> Subject: [mpich-discuss] Slurm and MPI_Comm_spawn My MPICH/Slurm job is failing when the call to MPI_Comm_spawn is made. The Slurm MPI guide https://slurm.schedmd.com/mpi_guide.html#mpich2<https://gcc02.safelinks.protection.outlook.com/?url=https%3A%2F%2Fslurm.schedmd.com%2Fmpi_guide.html%23mpich2&data=04%7C01%7Ckurt.e.mccall%40nasa.gov%7C85a0f5810bf64b7adaee08d9d21db0c7%7C7005d45845be48ae8140d43da96dd17b%7C0%7C0%7C637771847237637255%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000&sdata=ypExoCbDiU1nAf7Y8XHIj8Og9I3ZRK0IgKXZi0KHnCw%3D&reserved=0> specifically states that MPI_Comm_spawn will work going through Hydra’s PMI 1.1 interface. How do I ensure that it goes through that interface? Maybe we’ll have to rebuild Slurm to support PMI 1.1. This Slurm command yields the following and PMI 1.1 is not mentioned, although PMI 2 is. $ srun –mpi=list srun: MPI types are... srun: cray_shasta srun: pmi2 srun: none